Apparatus for controlling resistance in an electric circuit



July 20 ',-1926, 1,592,995 7 C. P. WALKER APPARATUS FOR CONTROLLING RESISTANCE IN AN ELECTRIQCIRCUIT Filed Sept. 50. 1922 MNTO/P: (Aw/Papa P 144M 3 Patented July 20, 1926 UNITED STATES E NT G F F l-C E GBANFORD I. WALKER, or LOS ANGELES, CALIFORNIA, AssIGivon 'ro L nwnLLYn IRON worms, A oonronarroiv or CALIFORNIA.

APARATUS FOR CONTROLLING RESISTANCE IN AN ELECTRIC CIRCUIT.

Application filed September 30, 1922. Serial No. 591,529.

My invention relates to electrically operated elevators and hoists and the principal olriect of the invention is to provide novel means for controllingsuch an elevator or hoist. In the standard form of elevators used in buildings, the elevator car is operated between top and bottom limits and it necessary to provide automatic means for preventing the car from running past these limits.

In the form of my invention illustrated, I utilize what is known as the l/Var-d-Leonard system tor controlling and operating the elevator motor. In this system a direct current generator is utilized, this generator being driven from any convenient source of power such, for example, as an alternating. current motor. The direct current generator drives a direct current motor, this direct current motor furnishing the power to raise and lower the elevator car. In the use of the Ward-Leonard system, the voltage and direction of polarity of the generator are controlled by variations in the generator field. lly decreasing the current in the field,

the voltage delivered by the gei'ierator may be reduced, and by reversing the direction 01': this current the polarity of the generator may be reversed. Since the normal speed or the motor under any given set of conditions directly proportional to the voltage impressed upon it and since the direction ot' rotation is dependent upon the polarity of the voltage impressed upon the armature of the motor, (the direction of polarity of the field of the motor being maintained con stant), it is evident that the speed and direction of rotation of the motor may be regulated by this manipulation of the generator field. Since the current in the generator field is small, it is possible to control a comparatively large generator with very small controlling apparatus and with small electrical losses, thus cutting down the first cost of the appa ati'is, the cost of maintenance of the apparatus, and the energy used. 7

In the operation of an elevator controlled by the ard-Leonard system, the speed of the elevator as it approaches either limit may be reduced by inserting resistance 'in series with the generator field. There are in general two methods of connection which will accomplish this. other words, the elevator motor canbe s1oweddown as it approach'es the limits otter travel (a) by having a switch, actuatedby the movement of the car, insert resistance in the field circuit of the generator or (b) by having separate rheosta'ts for the up and down directions in series with which. the slow down resistance is inserted. The disadvantage of the first system, noted above as (a), is that it is not possible to leave either terminal of travel at a speed greater than the speed at w rich the terminal was approached, due to the presence of slow down resistance in the field, circuit of the generator. The second system, noted above as (6), evercomes this objectionable feature but possesses another undesirable feature, which is, that when the car is stopped near the terminal landings and some of the slow down resist ance is in circuit with the generator field, it isimpossible to move the car forward on the first few points of the rheostat, making it necessary for the operatorto handle the rheost'at in a dillerent manner. Under these conditions the number of points the. controller has to be moved, to move the car, depends upon the amount'of slow down resistance in the generator field circuit, which in turn depends on the position of the car. For instance if the car is stopped a few inches away from a terminal landing, it is necessary for the operator to throw the controller over to the last point before the, car will move up to the landing.

It is'an object of my invention to overcome these disadvantages and to provide a slow down resistance which will stop the car at either limit of elevator travel regardless oi? the position of the car switch, the control device used being so constructed that the operation of the car switch is exactly the same-at the top and bottom floors as it is at. intermediate fioors.

A further object of my invention is to provide means to automatically slowdown the motor at either limit of the car travel, the control of this motor being'accomplished by -varying the direction and strength of the field current in the generator.

A still further object of'm'y invention is to pern'iit the car tobe. accelerated away from either limit oftra vel at the-same. rate it is accelerated at intermediate points by means of the car switch.

A still further object-of my invention is it possible to move the carv at a, slot speed and-through small distances in mg conta 31'? either direction at either end of its travel by a manipulation. of the controller in exactly the same manner that it would be manipulated to provide a similar movement at intermediate floors.

Further objects and advantages will be made evident hereinafter.

Referring to the drawings which are for illustrative purposes only,

F 1 is a diagram of a complete elevator control system utilizing my invention.

Fig. 2 is a simplified diagram showing the method by which the resistors are connected and disconnected from the circuit to accomplish the above designated objects.

In the term of the invention shown, 11 is the motor driving the elevator, this motor having an armature l2 and a field 13, the lield being connected between wires 1% and which are connected to any source of di rect current supply and which may be desig; nated as and for convenience The field ot the motor is, therefore, always of one polarity and of constant strength the voltage between the wires 14: and 15 being constant. The armature 12 of the motor is supplied from a direct current generator 21 having an armature 22, a series field 23, and a shunt tield Q-il. The shunt field 2% is provided with a field discharge resistor 25 to prevent excessive voltages building up on the hold when it is disconnected from. the remainder of the circuit. The direction of polarity of the field. 24: is controlled by an electrically operated revcrser switch 31. hav- 33. 2-3-1; and and having an up-coil 36 and a down-coil 37. A bralic magnet coil 38 .is also provided.

The movement of the car is controlled by a car switch 4-1 having a sliding arm 4E2 pivoted at (l3 and operated by means oil a handle 4 1-. The car switch may be convenicntly divided into rheostat 51 and a. rcvcrsing switch N. The rhcosta'l". 51 is provided with central contacts and and with outer contacts and inner contacts no. The contacts are hereinafter des gnated as prinu ry contacts the contacts being designated as intermediate coutncts. The contacts are arranged in two series extending to the right and left oi the contact The arm 42 connects the contact :3? to the contact 53 or when moved to the right or left. it connects each oi the ontacts 57 with the corresponding contact 56. An arm separated by insulation (3?) from the arm. i is provided in the reversing switch 61., th' arm 6:? making contact at all times with a sector 64- and in its central position making, contact with a dead sector 65. As the handie 4% is moved to the right or left, the arm 62 malzes contact with members 66 or 67 forming parts of the reversing switch 61.

Limit switches F1 and '72 are provided at the extreme top and bottom of the car travel,

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at all times to the wire 14: through a contact 33 and a wire Sal. Two series ot secondary contacts H5 and 87 are provided, the series .t secondary contacts being connected to ie contacts 56 to the right of the central position by means of wires so and the other set oi secondary coi'itacts 87 being connected by means of wires 82- with the contacts 56 at the left of the central position. The contact 82 is moved to the right or le'tt in the direction of the arrows 85:) opening the circuit to the sectors and 87 as the car approaches its limit ol travcl. A prin'iary resistor mil provided. this primary resistor being connected by means of taps placed at suitable intervals with the primary contacts Two secondary resistors 91 and 92 are provided. the resistor 91 being connected by sui able taps with the contacts and the r stor 02 being connected by suitable laps with the contacts 87. The switch 61 is uti lized to operate the switches 36 and. 3. find. thus control the direction of motion of the ar by controlling the polarit of the field 'lhis can readily be understood from the following description of its opcrat ion.

jrs tic handle i t. is moved to the right in the direction of the arrow l coutact establi. .zcii l)(,l.'\ .@i'l sectors 4land (il The sector (14; is fffiillliletl at all times with the wire ii and the sector (it; is connected through a wire and the limit switch '72 with the coil 36 on the switch 3 the other terminal of this coil being connected through the brake magnet. 38 with the wire 15. By euergit jug the coil 36 the contacts 32 and 33 are connected toe'etlmr one terminalv llll ot the field flel. being connected to the wire through a wire 103. and the other rerininul 10 ot the licld 33 1- being: connected through a wire m5 and a wire 106 with one terminal the resistance 90. the other terminal oi. sistance being connected through the lever 4-2 with the wire 1 1; when the lever near its center position. This connects the licld :34; in one direii-tion.

it the lever H is moved to the lctt iu the direction of the arrow D. the contact GT is energized from the wire 14- and the coil Si is energized through a wire 11.0 and the brake magnet 38. By energizing: the coil. Il'i'. the contacts 3% and 37 are closed and the field is connected in the opposite direction to that previously describes. It will thus be seen that the initial movement of the lever tel. in either direction energizes the coils 3G or 37 and thus determines the polarity of the field El, The manipulation of the 90, 91, and can be best undersets s, namely, the secondary contacts. of the slow down switch, the intermediate contacts 56 and the primary conliicts of the car si 1. it will also noted th at the secondary resistance 91 is connected by means tape with the contacts 85 and that the resistance connected by means of taps vith the contacts t will also he noted that the contacts 56 and 85 are connected tog ther in pairs as shown. As long as the car is su'liicient distance away from the limits oi? travel, the member 82 ot the slow down switch connects all of the cone tects 85 together, these contacts being in turn connected to the wire 14 through a wire 84-. V

In thedia-g 'rem. 2. the arm is shown at its lowest position This is the position. assumed when the or is running at full speed with all resistance cut out of the circuit. It will be noted that there is a circuit from the wire 84: through the segment 82 to the lowest contact 85 and to the lowest contact 56, this lowest contact 56 being connccted to the lowest contact 55. by means of the arm d2. In this position neither the resistort O nor theresistor is in circuit.

For the purpose of explaining the operation of the slow down device, let it he .asshined that the car is stopped at an intermediate position. hen the car is in this position, the. segjn'ient 82 will be in contact with all of the contacts 85 and 87. In order to move the car upward, the operator udvances thcslider, or controller lever, 42 in uright-hand direction as indicated by the arrow U in Fig. 1. In Fig. the advance of the sl der would be downward from the segment .52 and 51-3, inching successive contact between th" pairs oi contacts 55 and 56. lVith the initial nioi-einent of the slider. the entire resistance 90 is in circuit. thus giving a low strength cu rent in the gen erator field fi l and providii'ig' tor a slow starting of the motor; As the slider advanced and the successive pairs of: contacts 55 and 56 are connected, t-hecurrent tlovs through the segment tl'irough the successive conductors 86 and the slider 42, and thus cuts out increasing amounts of the re sistance 90 as the slider advances. Upon. the slider 42 reaching the lowest pair of contacts and ofi, the resistance 90is en. tirely removed from the generator field circuit and at such time the car will be moving upward. at full speed. it is evident that so long as the member 82 is in the position shown in the two figures, the arm 42 may be moved back and tortlncutting in or out resistance in the resistor 90, and regulating the generator field to give any speed desired by the operator quite indepeiident slow down switch.

As the car approaches the lii'nit 0' its travel, the inen'iber moves to the r the position shown in l i breaks contact successively "s 85, beginning; with the hot Vith the slide tion, as shown, the I speed, is evident that thi i a I the member 02, by S.1C"(ESSl'VQl Y'i370 one; contact with the contacts 85, will graduellj cut the resistor 91. into the circuit between the wires B l and thus iiserting the re sister 91 in. series with .grenerzitor field 24:. thereupon reducing the hold strengtl'i and slowing down the motor. The resistors 90. 91, and'92 are substantially similar to each other in their characteristics so that when the member has n'ioved to the position indicated by the dotted lines 110 in Fig. 2, and the contacts 85 are entirely disconnected theretroui. the current must then truvel through the resistor 91, with the re suit that a resistance is placed in circuit with the generator field 2% substantially equal. to the resistance 90..

l/Vith reference to Fig. 2, it will be perceived that with the segment 82 in the position indicated by the dotted lines 110. the movement of the slider 45.2 upwardly from the position shown will not ca. so any change in the resistance in the generator field circuitv owing to the fact that as the slider moves up each successive pair of contacts 55 and 56, and a r stance element is removed from the risistor 91. an equivalent resistance element added in the resistor 90 thus maintaining; a designated resistance r in the generator field circuit. Let it he assumed the the car is sto 'iped several inches from the upper terminal landing. T he see; most 82 would then be in the position indicated by the dotted lines 110. It is possible or the device shown to move the cnr up the hit ding at slow speed by advancing; to slider 4-9 over to the first notch. It will. .e evident that a further advance .ider 42 beyond the first notch cannot have 1c ell ect oi increasing' the speed of the oer upper direction, because ot the cuttn ot the resistor ill to the shine deg: t is cut out by the ot the slider. The can. however, be the upper lending ot the,

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I claim as my invention:

1. An apparatus for inserting resistance in an electric circuit independently at two ditto-rent points comprising: a rimary re sister having one end connected to one terminal oi said circuit; a scctmdar'y resistor having one end connected to the other terininal of said circuit; primary contacts con netted to successive points in said primary resistor; secondary contacts connected to successive points in said secondary resistor; intermediate contacts each directly connected to one of said. secondary contacts; means :for progressively connecting together all of said secondary contacts; and a slider adapted to connect any one t said primary contacts with a corresponding one of said in teruiediate contacts.

52'. An apparatus for inserting resistance in an electric circuit comprisii two resistors; equalizing means for cutting out one resistor as the other resistor is cut in progressively: and means tor short circuiting one of said resistors.

3. An apparatus for inserting resistance in an electric circuit comprising: two resisters; equalizing means for cutting out one resistor the other resistor is cut in progressively; and means independent of said equalizing means for short circuiting one ol said resistors.

An apparatus for regulating the re sist-ance in an electric circuit comprising: a primary resistor; a secondary resistor; a series of primary contacts, each primary contact being connected to a tap from said primary resistor; a series of secondary contacts each secondary contact being connect ed to a tap from said secondary resistor; an equalizing means for so connecting one of said primary contacts to a cooperating secondary contact that said primary resistor is out out of circuit as said secondary resistor is cut into circuit; and means tor connecting together all or partot said series oi secondary contacts.

An apparatus for regulating the resistance in an electric circuit comprising: a primary resistor; a secondary resistor; a series of primary contacts each n'iniary contact being connected to a tap from said nimary resistor; a series of secondary contacts each secondary contact being connects ed to a tap from said secondary resistor; an equalizing means tor so coi'inecting one of said primary contacts to a cooperating secondary contact that. said primary resistor is cut out of circuit as said. secondary resistor is cut into circuit; ant. a bridging member adapted to successively connect all of: said secondary contacts together.

6. An apparatus for regulating:- the resistance in an electric circuit comprising: a

primary resistor; a secondary resistor; a series of primary contacts each primary contact being connected to a tap from said, prin'iary resistor; a series oil secondary contacts each secondary contact being connec: ed to a tap from said secondary resistor; an equalizing means for so connecting one of said n'imary contacts to a. cooperating sccondary contact that said primary resistor is cut out of circuit as said secondary resistor s cut into circuit; and a bridging lllGITllJQl' connected to the first of said secondary contacts and so disposed that it can connect said first secondary contact successively with each of the other secondary contacts.

An apparatus for controlling resistance in an electric circuit con'iprising: a primary resistor; taps provided upon said prima I resistor; two secondary resistors; taps provided upon each of said secondary resistors; and switch means enabling the con nection of successive taps from the primary resistor with corresponding taps from either or" the secondary resistors so that the resistors thus connected present a mutually con'iplemental resistance within the circuit.

8. An apparatus for controlling resistance in an electric circuit comprising: a primary resistor; taps provided upon said primary resistor; two secondary resistors; taps provided upon each of said secondary resistors; switch means enabling the connection of successive taps from the priniiary resistor with corresponding taps from either of the secondary resistors so that the resistors thus connected present a mutually complemental resistance within the circuit; and means normally shorting the taps of the secondary resistors so that operation of the switch controls only the amount of the primary resistor in the circuit.

9. An apparatus for controlling resist ance in an electric circuit comprising: a primary resistor; taps provided upon said primary resistor; two secondary resistors; taps provided upon each of said secondary resistors; switch means enabling the connec tion oi? successive taps from the primary resister with corresponding taps from either of the secondary resistors so that the resistors thus connected present a mutually com plemental resistance within the circuit; and means normally shorting the taps oi the secondary resistors so that operation of the switch controls only the amount of the primary resistor in the circuit, said shorting means being shittahle to tree the taps of a given secondary resistor from a short.

in test mony whereot. l have hereunto set my hand at Losringeles, California, this th day of September,

ilPii'iIi'lFOPcD P. I BEER. 

